春季北大西洋三极型海温模态与中国东部极端低温事件频次年际变化关系的年代际增强  

Interdecadal Enhancement of the Interannual Variation Relationship between Spring North Atlantic Tripolar Sea Surface Temperature Mode and Extreme Cold Event Frequency in Eastern China

作　　者：梁静 孙建奇[2] 洪海旭 艾雅雯 华维[1] LIANG Jing;SUN Jianqi;HONG Haixu;AI Yawen;HUA Wei(School of Atmosphere Sciences,Chengdu University of Information Technology,Chengdu 610225;Nansen–Zhu International Research Centre,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029;Jiamusi Meteorological Bureau,Jiamusi 154000)

机构地区：[1]成都信息工程大学大气科学学院,成都610225 [2]中国科学院大气物理研究所竺可桢—南森国际研究中心,北京100029 [3]佳木斯市气象局,佳木斯154000

出　　处：《大气科学》2023年第4期1050-1064,共15页Chinese Journal of Atmospheric Sciences

基　　金：国家自然科学基金项目41825010。

摘　　要：本文研究了春季北大西洋海温异常与中国东部极端低温事件频次年际变化之间的关系。结果表明,北大西洋三极型海温异常模态(NATSST)在20世纪80年代末后可以显著影响中国东部极端低温事件频次第一主导模态的变化,但在80年代末之前却不能。进一步的机制分析表明,这两者关系之所以发生年代际变化,可能与NATSST激发的遥相关波列在20世纪80年代末前后期不同有关。在1960~1987年,NATSST激发的遥相关波列从北大西洋向中亚南部地区传播,路径偏南,对东亚地区大气环流的影响较弱,从而不能显著影响中国东部地区极端低温事件的变化。但在1992~2019年,NATSST能够激发南、北两支遥相关波列到达东亚。其中,北支波列与北大西洋涛动(NAO)有关,该波列从北大西洋出发沿欧亚中高纬向东传播,可以在蒙古地区造成异常气旋/反气旋性环流;南支波列从北大西洋出发沿欧亚中低纬向东传播,可以在中国中南部造成异常气旋/反气旋性环流。上述气旋/反气旋性环流有利/不利于中高纬冷空气南下,同时改变中国东部地区地表热通量,从而造成有利/不利于极端低温事件发生的气候背景条件,使得中国东部地区极端低温事件频次增加/减少。通过上述物理过程,NATSST在20世纪80年代末之后可以显著影响中国东部春季极端低温事件频次的年际变化,而在80年代末之前则不能。In this paper,the relationship of interannual variation between spring sea surface temperature anomaly in the North Atlantic and extreme cold event(ECE)frequency in eastern China is investigated.The results show that not before but after the late 1980s,the North Atlantic tripolar SST mode(NATSST)has significantly affected the first leading mode of ECE frequency in eastern China.Further mechanistic analysis suggests that such an interdecadal change in their relationship could be related to the difference in the NATSST-excited wave trains before and after the late 1980s.In 1960–1987,the NATSST-related wave train propagated from the North Atlantic to southern Central Asia,which was located more southward,and consequently,had a weak influence on atmospheric circulations and ECE in eastern China.However,in 1992–2019,NATSST could excite two wave trains.The northern train was associated with the North Atlantic Oscillation,propagating eastward from the North Atlantic to the mid-high latitudes of Eurasia,resulting in an anomalous cyclonic/anticyclonic circulation in the Mongolian region.The southern train propagated eastward from the North Atlantic to the mid-low latitudes of Eurasia,leading to an anomalous cyclonic/anticyclonic circulation in southern–central China.These cyclonic and anticyclonic circulations are,respectively,favorable and unfavorable to the southward movement of cold air from middle and high latitudes and change the surface heat flux in eastern China,consequently providing favorable and unfavorable climate background conditions for ECE occurrence.Through these physical processes,NATSST could significantly influence the interannual variability of the frequency of spring ECE in eastern China after the late 1980s,but not before that.

关 键 词：极端低温事件 北大西洋 波列 

分 类 号：P467[天文地球—大气科学及气象学]